1. Field of the Invention
This invention pertains to dryers, especially fabric dryers, and, more particularly, to means for reducing the fuel consumption necessary to heat the dryers increasing production of the dryers, and to reducing the emission of pollutants into the air from the exhaust of the dryers.
2. Summary of the Invention
It is an object of this invention to provide an energy saving system for a conventional dryer of fabric or other products.
It is another object of this invention to provide an efficient heat exchanger for heating air introduced into a product dryer.
It is still another object of this invention to combine an air heater with an exhaust pollutant remover.
Still another object is to increase production rates of a known dryer by simultaneously reducing the amount of energy necessary to heat the dryer.
Basically, these objects are obtained by combining on a conventional dryer a fresh air chamber in which fresh air is forced along a circuitous path. Tubes for removing the hot exhaust from the dryer are positioned to be exposed to the air in said circuitous path so that the exhaust is cooled simultaneously with the increase in temperature of the fresh air. The most desirable advantages from this system are that a significant amount of heat is recovered and transferred into the fresh air and thus reduces the amount of fuel consumed in bringing the air up to drying temperature. Secondly, this waste heat allows an increase in production rates of the dryer due to pre-drying without an increase in energy consumption. Thirdly, reducing the temperature of the exhaust gases facilitates removal of moisture and polluting particles. Fourthly, the pre-drying at a temperature generally intermediate room temperature and dryer temperature gives an improved feel and finish to the fabric.
In embodiments in which the exhaust collects in the tubes, the exhaust tubes are cleaned by being sprayed with a cleaning solution which helps to keep the interior of the tubes free from buildup and optimizes heat transfer between the exhaust gases and the fresh air. Also in the preferred embodiment the heated fresh air is introduced into the pre-dryer through pipes having nozzles which lie at angles of approximately 30.degree. to the vertical above and below the path of the moving product. In this way the air flows more smoothly along the product providing better heating and less vibration to the product. Preferably a portion of the heated air can also be diverted as required to supply make-up air to the main dryer sections also.